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Thermal textile pixels : Out-of-plane and in-plane heat transfer measurements of knitted textilesStöhr, Adriana January 2019 (has links)
The human body possesses a highly developed range of senses that help orienting oneself in everyday life. Especially when it comes to navigating, perceiving and reacting to the world around us, people tend to rely mostly on their vision and hearing. Suffering from an impairment of either one, or both of the predominating senses means having to counterbalance this constraint. People suffering from blindness and deaf-blindness compensate their impairment mainly by relying on their haptic perception. In this case, information is usually communicated by braille or vibrotactile means. To offer another non-visual and non-audial communication concept this thesis work introduces, the thermal textile pixels. A thermal textile pixel consists of an external thermal device, able to generate hot and cold thermal impulses, and a textile interface to transmit the signal. In order to design such thermal textile pixel it was crucial to be aware of the thermal transfer occurring through and within an textile. Numerous research studies have examined the thermal properties of textiles, especially in the context of clothing comfort, thermal comfort. Nevertheless, it should be considered that as a thermal textile pixel, the textile forms part of a system, governed by many parameters. Therefore, for designing such a device it is important to be aware of the temporal and spatial resolution of the thermal transmitted signal. These characteristics are influenced by multiple textile parameters. For this purpose, a thermal study has been performed investigating in- and out-of-plane signal transmission by textiles in combination with an external thermal device. Using an external thermal device such as a Peltier element allowed to expose the specimens to heating as well as to active cooling. Different knitted structures and material combinations have been examined to gain a first impression on the behaviour of thermal pixels. It was found that thickness and density were the most influential factors for out-of-plane heat transfer. In-plane was found influenced mainly by fibre conductivity. An anisotropic behaviour was noted in-plane, as well as between in- and out-of-plane for heat transfer. Investigating active cooling signals, it was found that a significant decline of performance was noted for all specimens. Plain PA was found to be most suitable for the transmission of heat signals. But did not perform equally well during active cooling phases. Plain Shieldex was observed to perform most steady during heating and active cooling.
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Nouzový zdroj elektrické energie s termočlánkem / Emergency back-up power source with a thermoelectric cellKubík, Roman January 2009 (has links)
This master´s thesis is directed to an research of thermoelectric cells as power sources. It is discoursing about general properities of thermoelectric cells and their using at practical aplications in the first part. Then a heating and cooling system is designed and made for a selected type of thermoelectric cell which represents the emergency back-up power source. In the next part a DC/DC step-up converter is designed for a selected type of thermoelectric cell. This converter generates the DC load voltage 12V. The converter is controlled by PWM with a carrier frequency 50kHz.
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Optimalizace vzduchotechniky zimního stadionu / Optimization of air conditioning of the ice stadiumZach, Daniel Unknown Date (has links)
This diploma thesis is divided into three parts: theoretical, calculation and experimental measurement. The issue of humid air and air-conditioning in winter stadiums is elaborately analysed in the theoretical part. In the calculation part, the dessertation focuses on the optimization of current draft of hockey hall air conditioning system. The hall is now in operation during the season, which means from September to March. In the dissertation are discussed two variants of the draft. The first variant is draft upgrade to year-round operation with condensing dehumidification. The second option is solved as a combination of air handler unit system and absorption dehumidification. This variant is also designed for seasonal and year-round operation of the ice rink. At the end of the dissertation are all of them compared in terms of annual costs. The experimental measurement is carried out on dehumidification of air from areas with high water gains, in this case swimming pool hall model. This problematics is solved by changing the speed of ventilator and using Peltier generator.
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